Waveguide assembly including a toroid having dielectric material therein

ABSTRACT

A waveguide assembly including a toroid of gyromagnetic material closely fitted within the waveguide includes first and second pieces of dielectric material dimensioned to substantially fill the void in the center of the toroid. A flexible tube having a normal diameter slightly greater than that of the spacing between the dielectric pieces is stretched, placed within the toroid between the pieces and then allowed to relax to lock the pieces in the center of the toroid.

United States Patent [191 Mason et al.

[ Oct. 23, 1973 [54] WAVEGUIDE ASSEMBLY INCLUDING A 3,686,590 8/1972 Dischert 1433/24.!

TOROID HAVING DIELECTRIC MATERIAL 3, CHM. WMm mwwhkwe.Mm Primary ExaminerPaul L. Gensler [75 1 Inventors: Robert Jean Mason, Medford; A"0mey Edwal-d J Norton et Norman Richard Landry, Willingboro, both of NJ. I

Assignee: I V- I ABSTRACT New York, NY. [22] Filed: 30, 1972 A waveguide lasslemblyfincludinghe toroid of gyr omngnet1c materia c osely itted wt in the waveguide in- [21] Appl. No.: 302,300 cludes first and second pieces of dielectric material dimensioned to substantially fill the void in the center 52 us. Cl. 333/24.1, 333/98 R wmid- A flexible having a diame- 511 int. Cl. H01p 1/32 l' F m P that 0f the f P 58 Field of Search 333/1.1, 24 G, 24.1, embed, Placed 333/242 24.3 I'Old between the pieces and then allowed to relax to lock the pieces in the center of the toroid. 1 [56] References Cited a 4 Claims, 2 Drawlng Figures 3,371,293 2/1968 Jones et al. 333/24.l

DIELECTRIC |3 -7 BODY l 29 l v Z ll'l. I ""UNW L WWW; r 25 I9 3 21 g I w I [)c 5 v A 55 27 3| IO SOURCE FLEX'BLE 2| GYROMAGNETIC TOROID TUBE DIELECTRIC BODY DIELECTRIC |3 ',/r 7| BODY i PATENlEnncrza Ian 3.768 040 .1 muum 2| GYROMAGNETIC TOROID TUBE DIELECTRIC BODY FIGI ' FIG 2 WAVEGUIDE ASSEMBLY INCLUDING A TOROID HAVING DIELECTRIC MATERIAL THEREIN This invention relates to a waveguide assembly and more particularly to waveguide structures which include a toroid of ferrite or garnet material therein, for example.

When a wire is placed through the void center of the toroid and a D.C. pulse is applied thereto, a D.C. magnetic field is set up within the toroid. When an R.F. microwave signal is propagated along the waveguide structure, for example, this biasing of the material can, dependent upon the bias conditions, provide phase shifting, isolating or limiting of this signal along the waveguide section.

When the toroid is placed, for example, in a rectangular waveguide it is normally centered between the broad walls of the rectangular waveguide. When the rectangular waveguide is dimensioned such as to support the R.F. waves in the TE] mode, for example, a

high electric field associated with the R.F. waves .is

present at this centered region. In order to provide increased loading on these waves to reduce the size of the waveguide and to increase the percentage offield at the center, the void in the center of the ferrite or garnet material is usually filled with relatively high dielectric material. Also, in order to provide symmetry tothese high electric fields in the center, the dielectric constant of the material placed in the center is usually close to that of the ferrite or garnet material. .The dielectric constant of the material can be made larger however to increase the percentage of the field atthe center.

In order to accommodate the placement of the biasing wire in the toroid, an aperture in the dielectric is required. It isdesirable that this aperture be located'in the center of the toroid to provide symmetry to the RF. signal waves and to reduce the insertion loss in such devices. A problem associated with the placement of a dielectric material in the center of the toroid is that a gap or a void of from l to thousandths of an inch is usually expected between the toroid slot and the dielectric. This'is due to thedimensional tolerances that can be placed on the size of the slot and onthe size of the insert. The ferrite and garnet materials are generally fragile. If the dielectric material fitted into the toroid slot is too tight and if this centered dielectric material expands more than the toroid material with change in temperature or the toroid materialcontracts more than the centered. dielectric material with temperature chance, improper functioning ofthe. toroid can occur.

Briefly,'in accordance withthe present invention the tion of the toroid when a D.C. pulse is applied thereto.

A further description follows in conjunction with the following drawings wherein:

' FIG. 1 is a perspective drawing of a typical assembled microwave phase shifter.

FIG. 2 is a perspective view of a portion of a toroidal body of gyromagnetic material having dielectric loading members therein according to the present invention.

Referring to FIG. 1, there is illustrated a waveguide phase shifter 10. The phase shifter includes a rectangular waveguide 11 having broad walls 13, 15 and narrow walls 17, 19. A toroid 21 is fixed between opposite broad walls 13 and 15 and centered between the narrow walls 17 and 19. The toroid 21 is of garnet material, for example, having a dielectric constant of about 15, for example. A biasing wire 23 extends within the slot 27 at about the center of toroid 21 and extends the entire length of the toroid 21. The ends of wire 23 are coupled to a D.C. current source 25. Upon the applica- "tion of a D.C. pulse along the wire 23, a D.C. magnetic field in the toroid 21 and about the slot 27 is established. The wire 23 is supported within'the slot 27 by meansof a pair ofdielectric bodies 29 and 31 and tube 33 extend sutstantially the full length of toroid 21.

Referring to FIG. 2, there is illustrated the manner in which the dielectric-bodies 29 and 31 are locked within slot 27 of the toroid 21. A flexible thin walled tube 33 of fluorocarbon material, for example, is passed through the toroid 21- and centered in the slot 27. The

thickness of the wall of tube 33 and the type of flexible at remote points from either end of the toroid 21. After the tube 33 is stretched, the dielectric bodies 29 and 31 are positioned withn the slot 27. The dielec'tricbodies 29 and 31 are dimensioned to be approximately of equal dimensions with the height h slightly lessthan one-half the height H of the slot 27. The width W of these dielectric bodies 29 and 31 is made slightly less than the width of the toroid slot 27 to allow these members to fit and substantially fill'the'void provided by the slot 27. Thedielectric bodies 29 and.31 are positioned within the 'slot 27 so that asmall void or gap 35 of a height G"remai'ns at about the center of the toroid 21 above disadvantages are avoided by a waveguide assembly comprising a conductive waveguiding member, a toroid of gyromagnetic material spaced within the conductive wave-guiding member, a plurality of dielectric bodies and a flexible tube placed between the dielectric bodies. The toroid'has a slot therein of a given dimension. The plurality of dielectric bodies are each dimensioned so that combined they substantially fill the slot, leaving a small gap of a given spacing between the bodies in the center of the slot. A tubular separator of flexible material of a relaxed dimension slightly larger than the spacing between the bodies 'is located within the gap to thereby hold the inserted dielectric bodies in position without the pressure sensitive properties of the toroid being degraded. A biasing wire may be positioned beside the tube in the gap'for causing magnetizawith the stretched tube 33 locatedwithin the gap 35.

The normal diameter of the tube33 is made slightly larger than that of the'h'eight of gap G. The diameter of the tube 33 when stretched is reduced so as to be slightly less than'that of the spacing G between the members 29 and 31. After thedielectric bodies 29 and 31 have been placed within the slot 27, the tube 33 is allowed to relax toward its normal diameter whereupon the tube expands in diameter, pushing the inserted dielectric bodies 29 and 31 against the inner top and bottom walls of the toroid 21.

\ In one arrangement according to the present invention, the tube 33 is of fluorocarbon material having a wall thickness of 0.006 inches and an outer diameter of 0.039.inches. The slot height of the toroid is 0.370

Placed beside the fluorocarbon tube 33 within the small gap is the biasing wire 23 required to develop the DC. magnetic bias for providing a phase shifter, isolator, etc. By placing the gap 35 in the center of the slot 27, improved microwave performance is achieved in that by locating the void near the center of the toroid the amount of coupling to high order modes is reduced. Otherwise, these higher order modes can result in a higher VSWR (voltage standing wave ratio) and increased insertion losses.

What is claimed is:

1. A waveguide assembly comprising:

a waveguide,

a toroid or gyromagnetic material positioned within the walls of said waveguide, said toroid having a centered aperture therein extending the length of the toroid a plurality of dielectric bodies dimensioned and positioned within said centered aperture to substantially fill the centered aperture leaving a small gap of a given spacing near the center of the aperture between the bodies,

a flexible tube having a normal diameter greater than said given spacing positioned within said small gap between the two dielectric bodies to hold the bodies within the aperture by the expansion of said tube toward its normal diameter.

2. The combination claimed in claim 1 including a biasing wire passing through said small gap.

3. The combination claimed in claim 1 wherein said dielectric bodies are two substantially equally dimensioned bodies.

4. The method of mounting dielectric bodies within a toroid positioned between waveguide walls and for providing an aperture through said toroid by which a biasing wire can be passed through said toroid comprising:

providing a toroid of gyromagnetic material having a centered aperture,

inserting a stretched thin walled tube of a normally larger diameter within the centered aperture of the toroid,

inserting bodies of dielectric material within the center aperture of the toroid so that said bodies with the stretched tube substantially fill the void of the slot,

relaxing said tube causing said tube to expand to said normal diameter thereof and push the dielectric bodies against toroid locking said bodies and said tube within the center of said toroid. 

1. A waveguide assembly comprising: a waveguide, a toroid or gyromagnetic material positioned within the walls of said waveguide, said toroid having a centered aperture therein extending the length of the toroid, a plurality of dielectric bodies dimensioned and positioned within said centered aperture to substantially fill the centered aperture leaving a small gap of a given spacing near the center of the aperture between the bodies, a flexible tube having a normal diameter greater than said given spacing positioned within said small gap between the two dielectric bodies to hold the bodies within the aperture by the expansion of said tube toward its normal diameter.
 2. The combination claimed in claim 1 including a biasing wire passing through said small gap.
 3. The combination claimed in claim 1 wherein said dielectric bodies are two substantially equally dimensioned bodies.
 4. The method of mounting dielectric bodies within a toroid positioned between waveguide walls and for providing an aperture through said toroid by which a biasing wire can be passed through said toroid comprising: providing a toroid of gyromagnetic material having a centered aperture, inserting a stretched thin walled tube of a normally larger diameter within the centered aperture of the toroid, inserting bodies of dielectric material within the center aperture of the toroid so that said bodies with the stretched tube substantially fill the void of the slot, relaxing said tube causing said tube to expand to said normal diameter thereof and push the dielectric bodies against toroid locking said bodies and said tube within the center of said toroid. 